The present invention relates to a process for producing a bridged cyclic polycarboxylic acid t-butyl ester that is useful, for example, as a sensitizer for resists, and to a novel norbornanepolycarboxylic acid t-butyl ester compound.
Adamantanedicarboxylic acid t-butyl esters and other bridged cyclic polycarboxylic acid t-butyl esters each have a polycyclic alicyclic group that improves etching resistance, and have a t-butoxycarbonyl group that is decomposed by action of an acid generated from a photosensitive acid generator to yield a carboxyl group. Accordingly, these compounds receive attention as sensitizers or dissolution inhibitors for photoresists. The addition of such bridged cyclic polycarboxylic acid t-butyl esters to resist resin compositions can yield sharp patterns. When the bridged cyclic polycarboxylic acid t-butyl esters are used as, for example, sensitizers for photoresists, they must be highly pure containing less impurities such as metallic components or coloring substances, in order to avoid deterioration of the properties of resists.
The adamantanedicarboxylic acid t-butyl esters and other bridged cyclic polycarboxylic acid t-butyl esters have been conventionally produced by allowing bridged cyclic polycarboxylic acids to react with isobutylene in the presence of an acid catalyst. This process, however, only achieves a very low yield of about 20% and is very insufficient as a commercial production process. Additionally, no process that can yield the bridged cyclic polycarboxylic acid t-butyl esters with high purity has been known.
Furthermore, conventional bridged cyclic polycarboxylic acid t-butyl esters are not always satisfactory as the sensitizers or dissolution inhibitors for photoresists, and demands have been made to provide substances with higher properties.
Accordingly, an object of the present invention is to provide a process that can commercially efficiently produce a bridged cyclic polycalrboxylic acid t-butyl ester.
Another object of the present invention is to provide a process that can easily produce a high-quality bridged cyclic polycarboxylic acid t-butyl ester containing less impurities such as metallic components.
Yet another object of the present invention is to provide a novel bridged cyclic polycarboxylic acid t-butyl ester that is useful, for example, as a sensitizer or dissolution inhibitor for photoresists.
After intensive investigations to achieve the above objects, the present inventors have found that the reaction of a bridged cyclic polycarboxylic halide with t-butyl alcohol or its alkali metal salt can produce a corresponding ester in a surprisingly very high yield, in spite of the bulkiness of the two components, and that a specific treatment of the reaction product can produce a highly pure bridged cyclic polycarboxylic acid t-butyl ester. Additionally, the present inventors have found a novel bridged cyclic polycarboxylic acid t-butyl ester during the investigations. The present invention has been accomplished based on these findings.
Specifically, the present invention provides a process for producing a bridged. cyclic polycarboxylic acid t-butyl ester, the process including the step of allowing a bridged cyclic polycarboxylic halide represented by following Formula (1): 
(wherein ring Z is a bridged cyclic carbon ring; X is a halogen atom; and m denotes an integer of equal to or more than 2, where ring Z may have a substituent) to react with t-butyl alcohol or its alkali metal salt to thereby yield an ester represented by following Formula (2): 
(wherein tBu is a t-butyl group; and ring Z and m have the same meanings as defined above.)
In this production process, a bridged cyclic polycarboxylic acid represented by following Formula (3): 
(wherein ring Z is a bridged cyclic carbon ring; and m denotes an integer of equal to or more than 2; where ring Z may have a substituent) may be allowed to react with a halogenating agent to thereby form the bridged cyclic polycarboxylic halide represented by Formula (1), and this bridged cyclic polycarboxylic halide may be allowed to react with t-butyl alcohol or its alkali metal salt.
The production process may include at least an adsorption treatment step of subjecting a reaction product to an adsorption treatment with an adsorbent, which reaction product is of the bridged cyclic polycarboxylic halide represented by Formula (1) with t-butyl alcohol or its alkali metal salt.
Furthermore, the production process may include at least a crystallization step of subjecting a reaction product to crystallization using solvent mixture of water and a water-miscible solvent, which reaction product is of the bridged cyclic polycarboxylic halide represented by Formula (1) with t-butyl alcohol or its alkali metal salt.
In the production process, the reaction product of the bridged cyclic polycarboxylic halide represented by Formula (1) with t-butyl alcohol or its alkali metal salt may be purified by successively subjecting to (A) a washing step of washing the reaction product with water, (B) an adsorption treatment step of subjecting the reaction product to an adsorption treatment with an adsorbent, and (C) a crystallization step to thereby yield a bridged cyclic polycarboxylic acid t-butyl ester.
Ring Z in Formula (1) includes, for example, bicyclic, tricyclic or tetracyclic bridged cyclic carbon rings such as an adamantane ring or norbornane ring.
In addition and advantageously, the present invention provides a norbornanepolycarboxylic acid t-butyl ester compound represented by following Formula (4): 
(wherein R is a substituent bonded to norbornane ring; n denotes an integer from 0 to 5, where substituents R may be different from each other when n is equal to or more than 2; tBu is a t-butyl group; and m denotes an integer equal to or more than 2.)